Materials for Sustainable Packaging
Major developments have been made in consumer consciousness, governmental regulations, and corporate standards to place a greater focus on sustainable products. One avenue brand owners of packaged goods have taken to shift toward being sustainable and eco-friendly is using materials in their biodegradable and renewable packaging. Bio-based polymers and paper are prime examples of materials used in sustainable packaging that have slowly replaced plastic, metal, and glass.
Creating bioplastics that can maintain the same barrier properties and functionalities as synthetic plastic films has gained traction recently. As a result, evaluations of bio-based polymers have increased. For a long time, paper has been a staple for packaging material. However, paper sizing and barrier coatings must be applied for the material to be viable for certain applications, such as preserving food freshness and preventing moisture, oil, and grease from permeating and being absorbed. Alginates serve as the ideal biomaterial that can provide a perfect mix of biodegradability, functionality, and sustainability to create sustainable packaging by forming barrier coatings, functioning as a paper sizing agent, and serving as a bioplastic resin.
Scogin® Alginates
Scogin® alginates from IFF are biopolymers derived from brown seaweed sustainably harvested from the coastlines of Norway. They are produced by extracting alginic acid from the seaweed and then adding sodium carbonate, creating sodium alginates.
Seaweed Raw Material ▷ Washing/Grinding ▷ Extraction ▷ Screening/Filtering ▷ Precipitation ▷ Alginic Acid ▷ Sodium Alginate
Chemically, Scogin® is composed of two monomers: (1-4)-linked ß-D-mannuronate, also known as the M monomer (M-block), and α-L-guluronate, also known as the G monomer (G-block). The polysaccharides formed from these monomers have differing proportions of M and G sequences, called blocks. Gelation is an important property of alginates in forming bio-based plastic films. The G-blocks provide sodium alginate gelling capabilities when exposed to calcium ions in water. Unlike other gels formed by hydrocolloids that require heat to induce gelation, alginates undergo gelation in cold water. This provides an easier mechanism for alginate gel creation.
The MG block ratio within the alginate ultimately determines gel strength, with alginates containing higher G-block content forming harder gels. The visualization of the mechanism in which gelation occurs is detailed above, referred to as the egg-box model. When calcium is not present, alginates can serve as rheology modifiers and film formers. Properties like this make alginates useful for barrier coating and paper sizing applications.
Scogin® Alginates in Packaging Applications
When Scogin® sodium alginates are dispersed in water, they serve as excellent film formers and rheology modifiers. Barrier coating and paper sizing applications rely on these properties to reduce the absorption or permeation of fluids.
Barrier Coatings
As sodium alginates reduce the surface porosity of paper, this also reduces the water vapor transmission rate, which is important for protecting the freshness of food, as in the case of barrier-coated paper used on food pouches.
As sodium alginates reduce the surface porosity of paper, this also reduces the water vapor transmission rate, which is important for protecting the freshness of food, as in the case of barrier-coated paper used on food pouches.
Paper Sizing
Paper that is not sized appropriately is not an ideal substrate for printing onto packages. This is due to the paper's porosity. In the case of paper sizing, Scogin® alginates create a film that covers and reduces porosity near the paper’s surface. This prevents ink systems from absorbing too deeply into the paper, which can cause a loss in image distinctness through blotting and potential color mixing.
In both paper sizing and barrier coating applications, the rheology-modifying properties of IFF’s alginates allow films to be formed with superior leveling properties that reduce surface defects and improve coverage, maximizing the efficacy of these applications. Scogin® alginates are biodegradable and have food contact approvals, making them ideal, as many food-based paper packaging producers aim to make their packaging more sustainable.
Bioplastics
Scogin® can also be used to create bioplastics that create sustainable packaging films. When Scogin® alginates are introduced to calcium ions in water, ionic bonds are formed in the alginate polysaccharide that cross-link and induce gelation. The gelling process also cross-links the alginate biopolymers to create castable thin films. When these gel films dry, they can serve as biodegradable films that can be further modified in terms of performance to replace traditional plastic films made using synthetic polymers.
How to Use Scogin®
Scogin® alginates are available in three grades. These grades, along with pertinent product specifications, are listed below.
Grades
|
Suggested use level (%)
|
Viscosity (1% solution, cP)
|
Mesh
|
|
|
0.1–1.0
|
15–25
|
18
|
|
|
0.1–1.0
|
50–70
|
25
|
|
|
0.1–1.0
|
350–500
|
28
|
When choosing a Scogin® grade for paper sizing or barrier coatings, viscosity should be the main specification to consider. This is because coating methods can vary widely depending on the viscosity range required to apply and obtain a desired coat weight. It should be noted that coatings with relatively high viscosities tend to have greater holdout properties on paper. This may be leveraged for paper with high porosity.
If Scogin® is being used for bioplastic applications, the visual below can be used to select a sequestrant and calcium source for the gelation, depending on the desired solution pH and gel properties.
Dispersion equipment is required to prepare solutions with Scogin® alginates. Scogin® products should be preblended with other dry formulation components prior to mixing at high speed. Scogin® alginate grades with finer mesh sizes tend to hydrate quickly. However, more shear is required with these grades to avoid lumping.
Summary
Scogin® alginates are sustainable and biodegradable polymers derived from brown seaweed. Alongside other IFF alginates, they provide the necessary functionality to create sustainable and high-performing food packaging materials. As natural film formers, gelling agents, and rheology modifiers, Scogin® has excellent utility in barrier coating, bioplastic film, and paper sizing applications. Also, since the biopolymers of Scogin® and other IFF alginates are sustainably sourced, safe, and have food contact approvals, they perfectly coincide with the aims of sustainable food packaging manufacturers. If you have questions about IFF alginates for your packaging application, ChemPoint is here to provide insights. Click below to inquire more about Scogin® alginates or obtain a sample.
